Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.
Fiddler is freeware and can debug traffic from virtually any application, including Internet Explorer, Mozilla Firefox, Opera, and thousands more.
An I thought the Fiddler name was a metaphor for the bow going back an forth like HTTP messages.
via http://itc.conversationsnetwork.org/shows/detail4073.html
If you've installed the recently released "Service Pack 2" (SP2) for
Windows XP, you have automatically installed a new firewall on your
PC that might be blocking VNC connections. To create an "exception"
for VNC, follow these instructions:
1. Click Start, click Run, type Wscui.cpl, and then click OK to open
Windows Firewall.
2. Click the Exceptions tab, and de-select the "Don't Allow Exceptions"
radio-button.
3. Click Add Port to display the Add a Port dialog box.
4. Enter port number "5900" or whatever port you've got VNC on that
PC to listen on (port number = 5900 + "VNC Display Number").
5. Select the TCP protocol.
6. In the Name field, type "VNC".
7. Click Change Scope to view or to set the scope for the port
exception, and then click OK.
8. Click OK to close the Add a Port dialog box.
That should do it! More info here:
http://support.microsoft.com/default.aspx?kbid=875357#7